We surveyed the amount and geomorphic role of wood in 18 pristine native forest streams (channel width: 3-6 m) throughout New Zealand, and quantified the characteristics associated with piece stability and geomorphic effect. Wood piece numbers (18-66 per 100 m) and volumes (85-470 m 3 ha -1) were similar to or greater than found in many streams throughout the world. Forest type and geographic location had no discernable influence on wood abundance at a particular site, possibly due to the confounding influences of local features (e.g., tree fall regime) and methodology ('snap-shot' survey of a dynamic system). Half the pieces that were geomorphically active had moved, suggesting that stable pieces did not necessarily dominate geomorphic activity. Tree ferns were an important contributor to wood abundance in many of the streams studied. IntroductionNumerous studies have characterized the amount (volume, density, or biomass) (HAR- MON et al., 1986;HERING et al., 2000) and role of wood in stream (TRISKA and CROMACK, 1980;BILBY and BISSON, 1998). Initially, much of this research was conducted in the Pacific Northwest of North America (LAMMEL, 1972;FROEHLICH, 1973; see GREGORY, 2003 for a review), but has since been conducted in other regions in the USA (e.g., New England, BILBY and LIKENS, 1980; Georgia, WALLACE and BENKE, 1984; Wyoming, YOUNG, 1994; Colorado, RICHMOND and FAUSCH, 1995), and throughout the world (e.g., New Zealand, MOSLEY, 1981; Australia, GIPPEL et al., 1996; France and the United Kingdom, PIEGAY and GURNELL, 1997; Central Europe, HERING et al., 2000). A conclusion common to many of these studies is that wood is an important component of forest stream ecosystems. Wood in streams can influence channel morphology, hydraulics and sedimentation patterns, which in turn influence nutrient dynamics and habitat for aquatic organisms (BISSON et al., 1987; see GREGORY et al., 2003a for a recent review).The abundance and functional importance of wood appears to vary by region, possibly due to characteristics of the riparian forest species (e.g., maximum tree height) and regional hydrology (GURNELL et al., 2002). For example, streams located in the redwood-dominated forests of northern California contain large volumes of wood (up to 4360 m 3 ha -1) that exert tremendous influence on channel morphology (KELLER and TALLY, 1979;KELLER et al., 1995). In contrast, streams in the coniferous forests of central Sierra Nevada, California (only 400 km southeast of the redwood study streams) have relatively low amounts of wood (up to 89 m 3 ha -1), which exerted only a minor influence on stream morphology (BERG et al., 1998).

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Abstract.A study ) of a dairy catchment stream entering an oligotrophic lake in an area of very high rainfall (,5 m year À1 ) yielded median concentrations of total nitrogen (TN), total phosphorus (TP), suspended sediment (SS) and Escherichia coli (E. coli) of 0.584, 0.074 and 3.7 g m À3 , and 405/100 mL (most probable number method), respectively. Trend analysis indicated significant (P , 0.01) decreases for TN (À0.08 AE 0.02 g m À3 year À1 ), TP (À0.01 AE 0.005 g m À3 year À1 ) and SS (À0.45 AE 0.14 g m À3 year À1 ) and were partly attributable to improved exclusion of cattle from the stream. Water balance calculations indicated that approximately one-half the rainfall left as deep drainage that by-passed catchment outlet flow recorders. Estimates of catchment yields for TN were improved by taking into account groundwater hydrology and concentrations from well samples. Storm-flow monitoring inflows exceeding the 97.5th percentile contributed ,40% of total loads leaving the catchment so that specific yields for SS, TN and TP augmented by groundwater inputs and storm flows were ,960, 45 and 7 kg ha À1 year À1 , respectively. These compared well with modelled results for losses from dairy farms in the catchment of 40-60 kg N ha À1 year À1 and 5-6 kg P ha À1 year À1 and indicated that attenuation losses were relatively small.

Abstract. Lake Brunner, an oligotrophic monomictic lake on the West Coast of the South Island of New Zealand, is under pressure from urban expansion and increased farming activity, which has led to concern for the effects on water quality in the lake. Epilimnetic nitrogen, phosphorus and chlorophyll a concentrations have increased since 1992, and Secchi depth decreased. This suggests an increased algal productivity caused by increased nutrient inputs, further supported by increased hypolimnetic oxygen depletion since 1992. These observations are likely to have resulted from enhancement of pasture drainage and effluent inputs from expanding dairy farms. The Vollenweider model predicted a mean phosphorus concentration in the lake close to that observed, from estimated catchment loading, suggesting that the Vollenweider model adequately estimated the retention of phosphorous. With the Vollenweider model the effects of potential future loading scenarios were explored. Modelling suggested that a 70% increase in phosphorus loading could turn the lake into a mesotrophic state. Trend analysis of total phosphorus suggests that, with present land uses in the catchment (intensive dairy farming) continuing to develop at the same rate using the same land management practises, this transition to a mesotrophic state will occur by 2040.